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<script>

var net = net || {};

(function () {

net.json = function(url)
{
    return net.ajax({
        url: url,
        parse: function(xhr) {
            return JSON.parse(xhr.responseText);
        }
    });
};

net.xml = function(url)
{
    return net.ajax({
        url: url,
        parse: function(xhr) {
            return xhr.responseXML;
        }
    });
};

net.ajax = function(options)
{
    return new Promise(function(resolve, reject) {
        var xhr = new XMLHttpRequest();
        var method = options.type || 'GET';
        var async = true;
        xhr.open(method, options.url, async);
        xhr.onload = function() {
            if (xhr.status == 200) {
                if (options.parse)
                    resolve(options.parse(xhr));
                else
                    resolve(xhr.responseText);
            }
            else if (xhr.status != 200)
                reject(Error(xhr.statusText));
        };
        xhr.onerror = function(error) {
            reject(error);
        };
        var data = options.data || null;
        if (data)
            xhr.setRequestHeader("content-type","application/x-www-form-urlencoded");
        xhr.send(data);
    });
};

net.probe = function(url)
{
    return net.ajax({
        url: url,
        type: 'HEAD',
    });
};

net._parseJSONP = function(jsonp)
{
    if (!jsonp)
        return {};

    if (!jsonp.match(/^[^{[]*\(/))
        return JSON.parse(jsonp);

    var startIndex = jsonp.indexOf('(') + 1;
    var endIndex = jsonp.lastIndexOf(')');
    if (startIndex == 0 || endIndex == -1)
        return {};
    return JSON.parse(jsonp.substr(startIndex, endIndex - startIndex));
};

// We use XMLHttpRequest and CORS to fetch JSONP rather than using script tags.
// That's better for security and performance, but we need the server to cooperate
// by setting CORS headers.
net.jsonp = function(url)
{
    return net.ajax({
        url: url,
    }).then(function(jsonp) {
        return net._parseJSONP(jsonp);
    }).catch(function(error) {
        return {};
    });
};

})();

</script>
